Jankovic's game deserted her in the second set against Safina
Top seed Jelena Jankovic's hopes of becoming the new world number one are on hold after she was beaten 7-6 (7-3) 6-1 by Dinara Safina in Los Angeles.
Jankovic was edged out of the first set on a tie-break before being swept aside by the Russian in the semi-finals of the East West Bank Classic.
The 23-year-old Serb would have overtaken compatriot Ana Ivanovic in the rankings if she had won the event.
"Hopefully my time will come," Jankovic said. "It is not the end of the world."
Safina's big-hitting game caused Jankovic problems from the start and, although she failed to serve out the first set at 5-4, a series of forehand errors from her opponent gave her the tie-break.
Jankovic completely lost her way after that and Safina quickly completed her victory.
The world number two, who had entered the tournament with a torn meniscus in her left knee, admitted she ran out of steam.
In the second set, I couldn't go anymore. My legs were shaking a little
"Dinara played very well," Jankovic explained. "I had some chances in the first set and then I played a bad tie-breaker. In the second set, I couldn't go anymore. My legs were shaking a little.
"I had an injury and was supposed to be out quite a long time and at least I had an opportunity to compete here, even though I wasn't at my best."
Safina will meet Flavia Pennetta in the final after the Italian beat Beathanie Mattek of the US 3-6 6-2 7-5.